I'm travelling from Kyoto to NRT airport next week. I'm taking a Hikari from Kyoto and need to connect to a NEX at some point. Is it better to transfer at Tokyo station or Shinagawa (assuming its a NEX that stops there). It looks like connection times are 17-20 minutes. Is that enough for both stations?

I assume a ticket agent in Kyoto can reserve me seats all the way through?